This is where an account puts a picture of themselves up for a couple of minutes. It is usually a nude or a very revealing picture and the poster sometimes pretends like they didn't mean to upload it. (see: bullshit) it is usually done as a desperate attempt to gain more followers and attention.

A picslip is when an anonymous (or anon) account will post a picture of themself for a short period of time. This usually happens when they reach a follower goal or if they're trying to increase their followers.